Glossary beginning with L

Volcano Term Definitions

Laccolithsearch for term

A body of igneous rocks with a flat bottom and domed top. It is parallel to the layers above and below it.

Laharsearch for term

A torrential flow of water-saturated volcanic debris down the slope of a volcano in response to gravity. A type of mudflow.

Landsatsearch for term

A series of unmanned satellites orbiting at about 706 km (438 miles) above the surface of the earth. The satellites carry cameras similar to video cameras and take images or pictures showing features as small as 30 m or 80 m wide, depending on which camera is used.

Lapillisearch for term

Literally "little stones." Round to angular rock fragments, measuring 1/10 inch to 2 1/2 inches in diameter, which may be ejected in either a solid or molten state.

Lavasearch for term

Magma which has reached the surface through a volcanic eruption. The term is most commonly applied to streams of liquid rock that flow from a crater or fissure. It also refers to cooled and solidified rock.

Lava Domesearch for term

Mass of lava, created by many individual flows, that has built a dome-shaped pile of lava.

Lava Flowsearch for term

An outpouring of lava onto the land surface from a vent or fissure. Also, a solidified tongue like or sheet-like body formed by outpouring lava.

Lava Fountainsearch for term

A rhythmic vertical fountainlike eruption of lava.

Lava Lakesearch for term

A lake of molten lava, usually basaltic, contained in a vent, crater, or broad depression of a shield volcano.

Lava Shieldsearch for term

A shield volcano made of basaltic lava.

Lava Tubesearch for term

A tunnel formed when the surface of a lava flow cools and solidifies while the still-molten interior flows through and drains away.

Limu O Pelesearch for term

Delicate, translucent sheets of spatter filled with tiny glass bubbles.

Lithicsearch for term

Of or pertaining to stone.

Lithospheresearch for term

The rigid crust and uppermost mantle of the earth. Thickness is on the order of 60 miles (100 km). Stronger than the underlying asthenosphere.

Lustersearch for term

The reflection of light from the surface of a mineral.